The field of use of the invention extends to process plants in which properties of fluids, such as, for example, temperature and pressure, are measured in order, for example, to increase the efficiency of a process or to keep to safety-relevant parameter intervals. The measurement of, for example, thermodynamic parameters of a fluid may also be of interest in non-industrial plants, for example in research, and in other fields of use. If the fluid is under pressure in relation to the atmosphere, the fluid has to be surrounded by a housing which is impermeable to the fluid. In order nevertheless to be able to make statements about the fluid contained in the housing, in the prior art use is made, for example for measuring the temperature, of protective tube devices which project at a proximal end out of the housing and project at a distal end into the housing such that the outer wall of the distal end comes into contact with the fluid within the housing.
In addition to such protective tube devices which are suitable, for example, for measuring the temperature via a temperature sensor accommodated in the distal end, the generally known prior art has also disclosed protective tube devices, such as, for example, Pitot tubes, which are suitable for measuring static and dynamic pressure or the total of static and dynamic pressure. However, the use of different measuring instruments within a housing is complicated, inter alia, because of the necessity of a connection adapted to the measuring instrument, i.e. an opening, in the housing wall.
Dynamic pressure is understood as meaning the pressure which arises because of a directed flow and which exerts a force and therefore a pressure, while static pressure arises because of the isotropic, collectively undirected particle movements in a fluid.